We retrospectively reviewed eight prospective epidemiological studies conducted between 1991 and 1995 for dual respiratory virus infection (DRVI) to determine the frequency, associated comorbid conditions, clinical presentations, and morbidity related to DRVI among immunocompetent persons. Two viruses were identified as the cause of 67 (5.0%) of 1,341 acute respiratory virus infections. DRVI was detected in patients from õ1 year to 79 years of age, in both sexes, and in many races. Forty-two percent of patients with DRVI were £4 years old. Fifty-eight percent of patients with DRVI had underlying chronic lung disease. DRVI was associated with upper respiratory tract illness; lower respiratory tract illness, including pneumonia; systemic influenza-like illnesses; and exacerbations of asthma or chronic obstructive pulmonary disease. All of the common acute respiratory viruses were identified; picornaviruses and influenzavirus A were the most common. The rate of DRVI (11.6%) was highest in the epidemiological studies in which cell culture, serology, and polymerase chain reaction were used together. Patients with DRVI were hospitalized significantly more often than those with respiratory infection due to a single virus (46.3% vs. 21.7%; P õ .01). The percentage of DRVIs increased proportionally with the number of diagnostic methods used. Respiratory illness associated with multiple viral pathogensMaterials and Methods has been reported infrequently. The majority of the studies have Study design. We retrospectively reviewed the charts inbeen published in the pediatric literature, with most infections cluded in epidemiological studies of community-acquired resreported to be due to respiratory syncytial virus (RSV) and a piratory virus infections conducted at our institution between second respiratory virus [1 -8]. The frequency of dual respira-1991 and 1995. A DRVI was defined as an acute respiratory tory virus infection (DRVI) varies widely in the literature, and virus infection and any combination of culture(s), serological the clinical relevance of DRVI is unresolved. Some authors test(s), or PCR(s) positive for two different viruses. An SRVI have found that the morbidity associated with DRVI is higher was defined as an acute respiratory virus infection caused by than that associated with single respiratory virus infection a single virus detected by either culture, positive serology, or (SRVI) [3], while other authors have not found that DRVIs PCR. The charts of all patients with DRVI in these epidemioare more severe than SRVIs [2, 5, 8 -12]. We performed a logical studies were reviewed by one of us (A.L.D.), and data retrospective review of prospective epidemiological studies of on demographics, comorbid conditions, date of onset of the respiratory virus infection carried out by the Acute Viral Respiacute respiratory illness, results of viral diagnostic tests, and ratory Disease Unit at Baylor College of Medicine between clinical presentation were recorded. A computerized database 1991 and 1995. We examined the inc...

Background:Respiratory tract viral infections (RTVIs) have been identified frequently in association with asthma exacerbations in children, but few studies have shown similar rates of viral infections in adults with asthma. Further studies using newer diagnostic techniques to evaluate the frequency of RTVIs in adults with acute exacerbations of asthma need to be performed.

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Respiratory syncytial virus (RSV) has been demonstrated to be an important cause of life-threatening pneumonia in adult bone marrow transplant recipients; however, its role in other immunocompromised adults has not been defined. We prospectively studied all adult patients with leukemia who were hospitalized at M. D. Anderson Cancer Center (Houston) during a 1-year period (November 1993 through October 1994). During a 19-week period when RSV was prevalent in the community, it was isolated from 9 (10%) of 87 patients with leukemia who developed an acute respiratory illness. In 6 (75%) of 8 patients with profound chemotherapy-induced myelosuppression, the RSV infection was complicated by pneumonia, with an 83% mortality rate. RSV appears to be an important cause of severe and often fatal pneumonia in myelosuppressed patients with leukemia.